The news comes as anticipated toxicology tests determined Harrouff had no synthetic drugs or hallucinogens in his system.

It was suspected in the aftermath of the gruesome slayings that Harrouff, a former Florida State University student, was on bath salts or the hallucinogen flakka, known as “the zombie drug.” But toxicology tests showed he had no trace of either substances in his system.

Harrouff has been charged with two counts of first-degree murder in the August 15 stabbing of John Stevens, 59, and his wife Michelle Mishcon, 53, who were sitting in their garage.

Responding officers reported a bloody scene at the home near Tequesta, where Harrouff was seen biting Stevens’ face and stomach.

He tested negative for other common drugs like cocaine and marijuana.

Authorities also released about 100 pages from Harrouff’s journal, including one where he writes, “feeling sad, depressed angry isn’t a way to live.” He also muses about the Renaissance, Picasso and nuclear weapons, according to CBS12.com.

On August 15, Harrouff was out to dinner with his parents when the young man stormed out of the restaurant, apparently angry over slow service.

Concerned about his behavior, the teen’s family called police and his fraternity brothers of FSU’s Alpha Delta Phi to help find him.

According to a police report, his mother, Mina called 911 before midnight, saying: "I don't know how to do this. My son has taken off. It seems like he's a little delusional. He says he feels immortal, like a superhero."

She told the operator that Austin had been "acting strange the last week or so" and claimed he had super powers.

Police responding to a 911 call of a gruesome attack found Harrouff after he had allegedly stabbed Mishcon and Stevens to death as they sat in their driveway. Investigators believe the attack was random.

Cops said he also attacked a good Samaritan who called 911 when he stumbled upon Harrouff biting Stevens’ face and stomach. That victim was airlifted to a nearby hospital, where he was treated and released after several days.

Police said it took several deputies and a K-9 to pry Harrouff off one of his alleged victims, as the teen was “abnormally strong” during the incident and was unaffected by a Taser.

“Help me, I ate something bad,” Harrouff reportedly told deputies.

He was hospitalized in the weeks following the murders, but later recovered and is currently being held in the Martin County Jail.